Device for encapsulating a radioactive resin-water slurry

ABSTRACT

A device and process wherein a metallic drum is lined with a layer of cement and vermiculite and evacuated. An injection header is fitted to and extends into the hollow interior of the lined drum to permit access of radioactive waste comprising a resin-water slurry. The hollow interior of the drum may fill with resins while the cement-vermiculite layer uniformly absorbs the water therefrom.

United States Patent Kucherer 1 1 July 31,1973

1 1 DEVICE FOR ENCAPSULA'IING A RADIOACTIVE RESIN-WATER SLURRY [76] Inventor: Harvey D. Kucherer, 1321 Foxwood Dr., Monroeville, Pa. 15146 [22] Filed: May 12,1971

[21] Appl. No.: 142,788

Related [1.8. Application Data Continuation-impart of Ser. No. 792,282, Jan. 21, 1969, abandoned.

US. CL..." 250/108 R, 250/106 S, 250/108 FS Int. Cl G21! 9/16, G211" 9/22 Field of Search 250/106 S, 108 WS,

250/108 FS, 108 R; 106/100; 252/3013 References Cited UNITED STATES PATENTS 12/1959 Struxness et al. 250/108 WS [/1968 Karter 252/3011 WS 3/1969 Nash et a1 250/108 R OTHER PUBLlCATlONS Barbour et al.: A. E. Board Report P.E.L. 102; Atomic Energy Board of Republic of South Africa; pages 18; Sec. 1965.

Primary Examiner-James W. Lawrence An0rney-A. '1v Stratton, Z. L. Dermer and M. B. 1,. Hepps [57] ABSTRACT A device and process wherein a metallic drum is lined with a layer of cement and vermiculite and evacuated. An injection header is fitted to and extends into the hol low interior of the lined drum to permit access of radioactive waste comprising a resin-water slurry. The hollow interior of the drum may fill with resins while the cement-vermiculite layer uniformly absorbs the water therefrom.

3 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION This invention relates to a device and process for the encapsulation of radioactive waste, and more particularly to prepared containers for receiving radioactive resin-water slurries.

The presently preferred technique for packaging radioactive waste materials, particularly those involving resin-water slurries, comprises centrifuging the slurry to dewater the resinous material, mixing the resins with cement in a cement mixer, and allowing this mixture to harden in a drum. The water from the slurry is generally poured into a prepared drum of cement mixed with vermiculite.

In certain reports, i.e. Report P.E.L. 102 issued by the Atomic Energy Board of The Republic of South Africa, it is suggested that the water receiving drum containing the cement-vermiculite mixture be evacuated prior to water ingress. This report indicates that the evacuated mixture absorbs more water, more uniformly, and without wet spots, i.e., areas where the cement is not entirely solidified due to the presence of an excess amount of water.

It should be apparent that present practices involve multiple processes such as dewatering and separate handling of the water and the solid materials, and involves the use of much equipment which is rendered radioactive such as a centrifuge and cement mixer. The above technique further involves substantial expense and some danger to operating personnel.

It is accordingly the object of this invention to encapsulate radioactive resin-water slurries directly thus simplifying the procedure and eliminating much equipment, and to produce a superior encapsulated package.

SUMMARY OF THE INVENTION The direct encapsulation of a radioactive resin-water slurry created for example from mixed bed ion exchanger resins in nuclear power plants is facilitated by providing an evacuated metallic drum which is completely lined with cement on a cement-vermiculite mixture and which includes an injection header or conduit allowing ingress of the slurry to the hollow interior of the container.

A drum is first prepared by placing a layer of cement or cement and vermiculite on its bottom. A cylindrical retainer assembly is then inserted such that an annular layer and a top layer of cement or cement-vermiculite can be poured. Subsequently the conductor injection header extending into the interior of the layers is fitted to the drum and to the lid thereof.

The drum is then evacuated so that air does not inhibit the ingress of the slurry and such that the vacuum produced aids in the uniform dewatering of the resinwater slurry.

Once the resin-water slurry has entered the chamber formed by the cement mixture, the water is drawn into and uniformly dispersed within the mixture. The chamber therefore is substantially free of water and its entire volume may be utilized to store resinous material.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention reference may be had to the accompanying drawing which shows a container surrounded by a shield and prepared for encapsulating a resin-water slurry.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, there is shown an encapsulation container 10, in accordance with this invention, surrounded by a shield 12 which may be of lead filled steel, as is known in this art. The container 10 essentially comprises: a drum l4 sealed by a lid 16, both of which may be suitably made of carbon steel; a liner 18 of cement or of a mixture of cement and vermiculite; and an injection header or conduit 20.

The container 10 is preferably prepared as follows:

A mix is prepared which suitably consists of any of the common forms of cement; either alone, or preferably in combination with vermiculite.

A bottom layer 22 of mix is placed in the drum 14. An inner retainer 24 which has an injection coupling 21 fitted thereto is then situated centrally within the drum l4 and is supported on the bottom layer 22. The inner retainer 24 preferably includes a cylindrical side portion 26 and a top 28 and a bottom 30. A plurality of openings 31 are provided in the cylindrical side portion 26 for egress of liquid. The openings 31 are preferably at the bottom of the retainer 24. The remaining volume of the drum l4 exterior to the retainer 24 is filled with the mix. Pins 25 may be provided to aid in maintaining the position of the retainer 24. The drum lid 16 may then be installed and locked to the drum 14 with a common bolted closing ring 32. The lid 16 should have its center contacting and supported by a flange 33 on the injection coupling 21.

When a sufficient amount of radioactive resin-water slurry has been accumulated to fill a container 10, the container 10 is placed within the shield 12. The shield 12 may be most conveniently utilized when comprising two sections; a drum support section 34 and a sleeve section 36 which can be releasably locked to the support section 34, as by pins 35. The injection header 20 is then fitted to the container 10.

The injection header 20 comprises a vacuum header 38 which is open and externally threaded at its bottom, as indicated by the numeral 39, and sealed at its top to a resin-water slurry injection pipe 40, as by welding. The external threads 39 are arranged to engage with threads 41 on the drum lid 16. The pipe 40 extends through the injection coupling 21 into the chamber 42 formed by the liner 18. A vacuum test line 44 is also fitted to the vacuum header 38. The slurry injection pipe 40 has a valve 46 fitted therein, and the vacuum line 44 has a vacuum gauge 48 fitted thereto. The pipe 40 extends to a resin-water slurry hold-up tank (not shown). A vacuum conduit 49 which is connected to vacuum pump (not shown) and which contains a valve 50 is connected to pipe 40 above the vacuum header 38.

To operate the composite structure, valve 46 is closed and valve 50 is opened and the vacuum pump is utilized to evacuate the drum 14 for example 7% to 9 pain for a 30 gallon drum with a 3 inch liner 18. Holes 52 are provided in the flange 33 to assure communication between the evacuated liner l8 and the vacuum header 38. Valve 50 is then closed and valve 46 opened to admit the resin-water slurry to the interior of drum l4.

The resin-water slurry entering through pipe 40 extending a short distance into chamber 42 is prohibited from eroding the bottom layer 22 of the liner 18 by the bottom portion 30 of the retainer 24. The resins accumulate within central chamber 42. The water passes through the holes 31 in the inner retainer 24 and is drawn into the liner 18. The water substantially uniformly wets the entire liner 18 since the vacuum constantly causes the liquid to migrate from relatively filled" regions to unfilled regions, i.e., those still possessing a relatively low pressure due to evacuation. The liner l8 subsequently hardens chemically. Valve 46 is closed when the container 10 is completely full. The "full state" may be ascertained by noting when the vacuum gauge 48 has returned to atmospheric pressure, i.e., when the vacuum gauge 48 has returned to approximately psia.

The filling process may be automated by utilizing a vacuum switch (not shown) to operate the valves 46 and 50. In operation, the switch would keep valve 46 closed and valve 50 opened until a vacuum of 7% to 9 psia, for example, is reached. Valve 50 would then be closed and valve 46 opened until sufficient slurry had entered to substantially eliminate the vacuum at which time valve 46 would be closed.

Although the preferred embodiment includes an essentially solid retainer 24 with a single ring of openings 31 proximate its bottom, the retainer may include several rings of opening 31, or may simply consist of a wire screen cage. The essential feature is that the retainer 24 allows egress of liquid from the chamber 42 without allowing resins to pass therethrough.

The injection coupling 21 should include internal threads 53. It will be recalled that the lid 16 also has threads 41. When the injection header 20 is removed, threaded plugs (not shown) should be inserted so as to engage threads 53 and 41 thus forming a double seal to egress of resins.

While there has been shown and described what is considered to be the preferred embodiment of the invention, modifications thereto will occur to those skilled in the art. The container 10 could also be utilized for slurries which has little or no resin content simply by reducing the size of chamber 42 and optionally filling chamber 42 with vermiculite. Accordingly, it is not desired that the invention be limited to the specific arrangement described but rather that the true scope of the invention be delineated in the appended claims.

What is claimed is:

1. Apparatus for encapsulating a radioactive resinwater waste slurry of the type removed from nuclear reactor power plants comprising:

an outer container made of a material which functions as a radioactive shield;

a drum having a closable lid in said outer container;

a dry mixture of construction cement and vermiculite in the base of said drum;

a closed inner container in said drum, said inner container being of the same configuration as the drum but of a size substantially less than said drum and having the space between the drum and inner container walls filled with said mixture;

said mixture further including a layer overlying the top of said inner container;

means in said inner container establishing communication between said container and the mixture in said space;

means extending from the inner container through the overlying layer and the drum lid which defines an opening;

a pipe extending through said opening and terminating at one end in said inner container and arranged at its other end to be selectively connected to a resin-water slurry source and to a vacuum pump, and valves between said slurry source and pump and said pipe respectively;

whereby upon evacuating said inner container of air, the resin-water slurry is caused to flow into the inner container, the water therein gravitating through the means in the container into contact with said mixture in the space which later forms a solid mass while the solid particles in the slurry remain in the container.

2. The apparatus according to claim 1 wherein the means establishing communication with the mixture in said space comprises multiple openings in the base of said inner container for permitting egress of liquid into contact with said mixture in the space.

3. The apparatus according to claim 1 wherein the means defining the opening in the overlying mixture layer comprises a cylindrical injection coupling having threads on its upper end for receiving a plug used to seal the resin-slurry mixture in said drum and container; and

a vacuum header coupled to said lid and overlying said opening, and wherein said pipe extends through the vacuum header and said opening. 4 k 4 

2. The apparatus according to claim 1 wherein the means establishing communication with the mixture in said space comprises multiple openings in the base of said inner container for permitting egress of liquid into contact with said mixture in the space.
 3. The apparatus according to claim 1 wherein the means defining the opening in the oVerlying mixture layer comprises a cylindrical injection coupling having threads on its upper end for receiving a plug used to seal the resin-slurry mixture in said drum and container; and a vacuum header coupled to said lid and overlying said opening, and wherein said pipe extends through the vacuum header and said opening. 